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Pioneers of another sort

DR. E. KIRSTEN PETERS

Updated:
March 26, 2010, 6:21 p.m.

Sometimes it pays to spend 10 years in detention. Not that a person would ever want that to happen, but if it did — could you put the time to good use? That’s a question I’ve asked myself. I’ve also asked my students exactly the same thing. The value of a good high school or college education, I say to them, is that it should give you the tools to use time like that well. What would you do with it? One thousand years ago an Arab man named Ibn al-Haytham found himself under house arrest in Cairo. That far back ago in time, we don’t know much of the specifics of Ibn al-Haytham’s life. But we do know he was a towering giant of an intellectual in his day. If you give a thinking person ten years to think, don’t be surprised if there are some powerful results in the end. In Ibn al-Haytham’s case, a good argument can be made that the ten-year gap in his life was quickly followed by the release of his major book on optics. That book was pivotal to our lives today, because optics was hardly the only issue it addressed. In the ancient world — more than 1,000 years before Ibn al-Haytham’s own life — Greek philosophers had two main theories of vision. One theory (advanced by Ptolemy and Euclid) was that “vision rays” left the eye and went out to objects around us in the world. The other was put forward by Aristotle. The great philosopher had argued a “form” of some sort comes from an object in the world around you and enters your eye so you can see it. Ibn al-Haytham pointed out, first, that not all the ancient Greek authorities could be right, since they followed two contradictory ideas on the subject. Then he noted that we don’t have vision unless there is light around us: either light from the object we are seeing (like a lamp) or light rays from reflected light (like sunlight in the day). So light, first, is what we need to understand in order to better understand vision. Using only logic like this and a few simple experimental materials — a pinhole in a curtain or a hollow straight tube — Ibn al-Haytham went on to deduce a great deal about modern optics. Light rays travel in straight lines. Light on flat mirrors is reflected in one set of ways, and on curved mirrors in others. Light is refracted (bent) when it moves from air to water. Most importantly of all, Ibn al Haytham did all this good work using experiments and observations, writing out for his readers what they could do to show themselves the same evidence he had seen and reach the same conclusions. That’s not bad for 10 years of work under nice conditions. For 10 years in detention, it’s really a remarkable feat. Two hundred years passed after the death of the Arab scholar before a Christian monk took up a translated volume of the work and saw its value. Roger Bacon was our hero’s name. He was not Francis Bacon — there are two Bacons rattling around in history. Roger Bacon repeated some of Ibn al-Haytham’s experiments — but he also endorsed for the Christian tradition this new method of gaining new knowledge about the natural world. Experiments and testing of physical facts, Bacon argued, were the most productive ways to learn about the physical world around us. Others around Bacon were soon on board with the program, and Medieval Europe began to have at least an inkling of the modern, scientific method. The reason science and engineering have been able to progress so much in our lifetimes is that the method of running experiments and testing results is enormously successful. But in the old world, it was far from clear that this approach would lead to the most sound results. We owe Ibn al-Haytham and Roger Bacon a lot, not just for their good work on optics, but for recognizing the power of the scientific method that has given us so much today. — Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard. Follow her on the web at rockdoc.wsu.edu and on Twitter @RockDocWSU. This column is a service of the College of Sciences at Washington State University.